Generalized Birkhoff theorem in the Poincare gauge gravity theory

The analysis of the validity of Birkhoff's theorem about the uniqueness of the spherically symmetric solution of the gravitational field equations is extended to the framework of the Poincare gauge gravity theory. The class of models with the most general Lagrangians of the Yang-Mills type constructed from all possible quadratic invariants of the curvature and the torsion is considered, including both parity-even and parity-odd sectors. We find the families of models in which the weak and strong versions of the generalized Birkhoff theorem arc valid, by making use of the double duality technique.